C(28,3,2) = 131
Method of Construction: simple construction: combined (27,3,2) and (27,2,1)-coverings
Lower Bound: Schonheim
1 6 8
2 4 9
3 5 7
10 15 17
11 13 18
12 14 16
19 24 26
20 22 27
21 23 25
1 10 19
2 11 20
3 12 21
4 13 22
5 14 23
6 15 24
7 16 25
8 17 26
9 18 27
1 16 22
2 17 23
3 18 24
4 10 25
5 11 26
6 12 27
7 13 19
8 14 20
9 15 21
1 5 9
2 6 7
3 4 8
10 14 18
11 15 16
12 13 17
19 23 27
20 24 25
21 22 26
1 14 27
2 15 25
3 13 26
4 17 21
5 18 19
6 16 20
7 11 24
8 12 22
9 10 23
1 11 21
2 12 19
3 10 20
4 14 24
5 15 22
6 13 23
7 17 27
8 18 25
9 16 26
1 12 20
2 10 21
3 11 19
4 15 23
5 13 24
6 14 22
7 18 26
8 16 27
9 17 25
1 2 3
4 5 6
7 8 9
10 11 12
13 14 15
16 17 18
19 20 21
22 23 24
25 26 27
1 17 24
2 18 22
3 16 23
4 11 27
5 12 25
6 10 26
7 14 21
8 15 19
9 13 20
1 15 26
2 13 27
3 14 25
4 18 20
5 16 21
6 17 19
7 12 23
8 10 24
9 11 22
1 18 23
2 16 24
3 17 22
4 12 26
5 10 27
6 11 25
7 15 20
8 13 21
9 14 19
1 13 25
2 14 26
3 15 27
4 16 19
5 17 20
6 18 21
7 10 22
8 11 23
9 12 24
1 4 7
2 5 8
3 6 9
10 13 16
11 14 17
12 15 18
19 22 25
20 23 26
21 24 27
1 2 28
3 4 28
5 6 28
7 8 28
9 10 28
11 12 28
13 14 28
15 16 28
17 18 28
19 20 28
21 22 28
23 24 28
25 26 28
24 27 28